3206 IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY, VOL. 21, NO. 3, JUNE 2011 In-Field Current Transport Properties of 600 A-Class Coated Conductor Utilizing IBAD Template Masayoshi Inoue, Rene Fuger, Kohei Higashikawa, Takanobu Kiss, Satoshi Awaji, Masafumi Namba, Kazuo Watanabe, Yasuhiro Iijima, Takashi Saitoh, and Teruo Izumi Abstract—We have investigated critical current properties of 600 A/cm-class (GdBCO) coated conductor (CC) deposited on IBAD template. 2.5 thick GdBCO layer has been obtained by pulse laser deposition without degradation of critical current density by an improved heating condition in reel-to-reel deposition process. This enables stable production of long length CC with (77 K, self-field) of 600 A/cm-w. In-filed has also shown high value e.g., , - , , - . These experimental results obtained in a wide range of bias conditions of temperature , magnetic field and field angle are useful as a fundamental data for design of superconducting devices such as coil winding and magnet. Furthermore, we have also shown that our proposed analytical expression of electric field vs. current density characteristics agrees well with the experimental results. This analytical expression allows us to predict property as well as characteristics at arbitrary conditions of and . Index Terms—Coated conductor, critical current, current trans- port property, characteristics, high- superconductor. I. INTRODUCTION L ONG length RE-123 (RE: Rare Earth, Y, Gd etc.) coated conductors (CCs) have been developed [1]–[4] and some projects on research and development of practical supercon- ducting devices such as electric power cable, transformer using RE-123 CCs are in progress around the world [4]–[9]. For improvement of performance of practical applications, enhancement of engineering critical current density ( “crit- ical current ”/“total cross-section area includes whole layers”) is required. In the case of RE-123 CCs, there are two ways to Manuscript received August 03, 2010; accepted December 13, 2010. Date of publication January 28, 2011; date of current version May 27, 2011. This work was supported by New Energy and Industrial Technology Development Organ- ization (NEDO) as the Project for Development of Materials & Power Applica- tion of Coated Conductors, M-PACC and JSPS: KAKENHI (20360143). M. Inoue, R. Fuger, K. Higashikawa, and T. Kiss are with the Department of Electrical Engineering, Graduate School of Information Science and Electrical Engineering, Kyushu University, 744 Motooka, Nishi-Ku, Fukuoka 819-0395, Japan (e-mail: inoue@ees.kyushu-u.ac.jp). S. Awaji, M. Namba, and K. Watanabe are with the High Field Laboratory for Superconducting Materials, Institute for Materials Research, Tohoku Uni- versity, Aoba-Ku, Sendai 980-8577, Japan. Y. Iijima and T. Saitoh are with the Fujikura Ltd., Koto-ku, Tokyo 135-8512, Japan. T. Izumi is with the Superconductivity Research Laboratory, ISTEC, Koto-ku, Tokyo 135-0062, Japan. Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TASC.2010.2102000 the enhancement of ; 1) improvement of critical current den- sity , and 2) increase of thickness of superconducting layer without degradation of . The latter is effective way because: 1) high- around 2–3 has already been established in long length RE-123 CCs fabricated by reel-to-reel process, and 2) the ratio of area of superconducting layer to that of other layers is typically less than 1/50. This means the thickness of superconducting layer only affect the increase of cross-section area while it can increase effectively. However, making thick RE-123 films is not easy. Actually, it was reported that of RE-123 films fabricated by pulsed laser deposition (PLD) process shows saturation against increase of thickness [10], [11]. In order to overcome this saturation issue, Fujikura Ltd., have modified the heating conditions of PLD process in reel-to-reel fabrication system. Using this system, they have succeeded to prevent saturation up to about 6 thickness and to fabricate high- (GdBCO) CCs. For example, of 1,040 A/cm can be obtained in short sample with thickness of about 6 , and now they plan the fabrication of RE-123 CCs over 1 km with an of over 500 A/cm-w [12]. These high- properties are confirmed at 77 K and self-field, but in-field current transport property is not yet clarified even though this kind of high- CCs is possible next standard RE-123 CCs for practical applications such as coil winding, magnet and so on. In this study, we have investigated in-field current transport property of 600A/cm-class GdBCO CC at wide conditions of temperature , magnetic field , and magnetic field angle . Furthermore, we have also discussed the applicability of our proposed analytical expressions of characteristics based on a framework of the percolation model and the scaling law of the flux pinning properties [13]. II. EXPERIMENT A. Sample 2.5 thick GdBCO film was made by PLD method on a substrate composed of 100 thick Hastelloy, 1.1 thick made by the ion-beam assisted deposition (IBAD), and 0.5 thick by PLD. Ag was also deposited on GdBCO film as a protection layer. For detailed measurement of current transport property, we cut out 1 cm long piece from long length GdBCO CC and then made microbridge - - by using photolithograph technique and wet-etching process. at 77 K & self-field and critical temperature were 600 A/cm-w and 93.0 K, respectively. 1051-8223/$26.00 © 2011 IEEE